HOMEWORK, Macroeconomics

How do you figure out the answer to this question: You are a student at a university. You pay $8,000 per year in tuition, $5,000 per year in living expenses, and $1,000 per year for books. Were you not in school, you could earn $15,000 per year and you would not live with your parents. What is your economic cost of a year in college?